DRT proposes to develop an innovative, low cost, reliable, clinical, fluidic multiple medical gas monitor for O2, N2, CO2, N2O and any one of six inhalation anesthetics. Gas concentrations of an N-constituent mixture are uniquely determined by simultaneously solving the constitutive equation and N-1 equations relating measured mixture properties to concentrations. Our successful Phase I, three-gas, proof- of concept demonstrator gas monitor will be refined in Phase II and used as a tool too develop the clinical five-gas system. In phase II four properties will be measured fluidically: viscosity (pressure and flow across a capillary); density (pressure and flow across an orifice); specific heat (Joule-Thompson Effect/throttling nozzle); and, ratio of specific heats (speed of sound/sonic oscillator). Measurements will be digitally processed and concentrations displayed in real time on a virtual instrumentation, full-color, CRT with clinical accuracies from 0.1 to 1-percent. The system performance will be designed to be comparable to, or better, than that of conventional full-function monitors but will cost less than half due to replacement of complex sensors with fluidic devices. Sensor concepts for additional independent properties, such as thermal conductivity, will be examined for possible expansion of our system.